Drifting valve for locomotives



prll 3U, 1935. c. STERN DRIFTING VALVE FOR LOCOMOTIVES Filed May 22, 1955 5 Sheets-Sheet l blica/wz 11,6

prll 30, 1935. c. STERN 1,999,643

DRIFTING VALVE FOR LOCOMOTIVES Filed May 22, 1955 5 Sheets-Sheet 2 :n :il *WFT-w pr 3U, 1935. c. STERN T11,999,643

DRIFTING VALVE FOR LOCOMOTIVES l Filed May 22, 1955 5 Sheets-Sheet 5 n; I QWQMO April 3U, C, STERN DRIFTING VALVE FOR LocoMoTvEs Filed May 22, 1955 April 30,1935. l XC, STERN 1,999,643

DRIFTING `VALVE FOR LO'COMOTIVES Filed May 22, 1953 5 Sheets-Sheet 5 19 I zo :L7 15 l| I 2,1 Y l Q2 l* 2.7

MHH 25 ,26 Il. 25 j z5' (kalfZas ,Sfera Patented Apr. 3o, 193s i 1,999,643

UNITED srArEs PATENT OFFICE DRIFTING VALVE FOR LOCOMOTIVES Charles Stern, Jersey City, N. J assignor to Ardco Manufacturing Company, Hoboken, N. J., a corporation of Delaware Application May 22, 1933, Serial No. 672,340 12 Claims. (Cl. 121-137) The present invention relates to improvements Figure 2 is a front view of the same. in drifting valves for locomotives, and has for an Figures 2a and 2b are sections of check Valves. object certain improvements over the `devices Figure 3 is an enlarged sectional view of the shown and described in my prior two co-pending drifting and control valves in position when the 5 applications entitled, respectively, Lubricator conlocomotive is moved under full steam and when 5 trolled drifting valve for locomotives, led August at rest.

24, 1932, Serial No. 630,307, and Governor con- Figure 3a is a vertical sectional view of a. cylintrolled drifting valves for locomotives, filed Sepder cock in closed position. tember 29, 1932, Serial No. 635,445. Figure 4 is a View similar to Figure 3 taken on In common with the objects of these prior inan enlarged scale showing the position of the parts 10 ventions and applications, the present invention when the throttle is closed and the locomotive contemplates an improved drifting valve which drifting. l will assure the delivery of an adequate amount of Figure 5 is a vertical section of one of the cylboiler steam Yto the locomotive steam chests and inder cocks in the open position, and

cylinders as soon as, and throughout the time Figure 6 is a section taken on the line 6 6 in 15 that, the throttle is closed and the locomotive Figure 1. Y

permitted to drift, in order that the proper lubri-r Referring more particularly to the drawings, cation and moisture may be supplied to the valves Ill designates generally a locomotive having the and pistons, that vacuum in the cylinders may locomotive steam chests I I and the locomotive be eliminated and to the end that the other adcylinders I2. Figure 1 shows main air reservoir 20 vantages of supplying drifting valve steam to the connected to valve 3| in cab, and this valve is conlocomotive steam chest and cylinders may be had. nected to pipe 29 which is in communication with The present invention relates more particuinlet valve 53 in air valve casing 52, Figures 3 4. larly to an improved form and construction of The air chamber 55 beneath the inlet valve 53 control valve for regulating the opening and closcommunicates freely with the pipe 48 which leads 25 ing of the drifting valve, such control valve being to the cover plate 45 of drifting valve 32 for suppositive and reliable in its action and being of plying air to interior of bellows 43 (Figures 3 4). simple construction in which the parts are such A branch pipe 25 leading from pipe`29 communias to have long life and not easily Iget out of order. cates with the cylinder cocks I5 as shown in Fig- 30 The invention also has for an object to proures 1 2. 3g vide an improved form of the drifting valve in Figure l shows drifting valve 32 attached to which the Valve will open and close reliably and locomotive steam dome i4 with standard globe quickly in response to its actuating medium, valve 3l connected between dome I4 and valve which is compressed air in the instance shown in opening 35, as shown in Figure 6. An emergency 35 the drawings. extension handle 38 connected to valve 3l extends 35 A further object of the invention is a joint into locomotive cab.` Pipe 49 connects to drifting operating hook-up of the cylinder cocks and driftvalve 32 and to cross pipes 59 leading to and coming valve whereby when the vcylinder cocks are municating with both of the locomotive steam closed the drifting valve will be placed in a pochests Il. In the pipe 59 are check valves 5I for tential position for the opening and closing of a preventing the steam chest pressure from getting 40 supply of boiler steam to the locomotive valve back into the pipe 49 as shown in Figure 2. Pipe chests and cylinders. ThisV combination com- 'II leading from cross pipe 50 alsoconnects to pletely eliminates the possible human neglect to port l2 in the large cylinder 66 of control valve open and shut the drifting Valve. as shown in Figures 3 4. Figure 1 also shows With the foregoing and other objects in view, locomotive steam pipe I3 to which is connected 4,5 the invention will be more fully described hereinpipe 61 leading to large cylinder 65 of control after, and will be more particularly pointed out in valve, as shown more clearly in Figures 3 4. the claims appended hereto. Superheated steam is supplied to the steam In the drawings, wherein like symbols refer to chests II through the steam pipes I3 whenever 5o like or corresponding parts throughout the sevthe throttle valve is open.l The steam dome is 50 @m1 views, shown at I4 and the drifting valve is indicated Figure l is a diagrammatic side view of a locoas being connected to this steam dome for the motive shown equipped with an improved driftpurpose of receiving steam at boiler pressure ing valve system constructed in accordancewith therefrom. the present invention. The cylinder cocks are mounted as usual in the 56 lower portions of the ends of the locomotive cylinders I2 and such cylinder cocks are shown in Figures 3a and 5.

The cylinder cock bodies or casings are represented at I5 and the same are providedV with threaded shanks I6 for screwing into the threaded sockets in the locomotive cylinders I2. The cylinder cocks are provided with valves. l1 adapted to close upwardly against valve seats I8. Below the valve seats I8 are blow-off vents or passages I9 and below such passages are diaphragms 23 through which the valve members I1 reciprocate. Such valve members are carried upon plates ZI resting on the upper portions of bellows 22 which are free to expand and contract within the casing I5, such ,casing being preferably freely vented to the atmosphere so as to allow free atmospheric pressure to bear at all times upon the pleats or convolutions oi the bellows 22. The lower portion of the bellows contains a flange ring 23 extending beneath the casing l5 and clamped against the casing by head 24 through the use of bolts 25. The compressed air pipe 26 communicates with the interior of the bellows, as shown by the arrows in Figure 3a.

The stop bolt 21 is adapted to be moved up to permanently close the valve I1 should the bellows become ruptured Vor should the-device get out of order for any reason. The stop bolt 21 is formed with an integral reducedscrew plugV 28 threaded adjustably into the head plate 24 and having a lower exposed polygonal end to which a wrench may be attached for securing the plug and the stop bolt up and down. l

Figure 3a shows by the arrows that compressed air is being let into the bellows with the effect that the bellows 22 is expanded and the valve I.' closed against its valve seat I8. This is the normal running position of the parts as will be well understood.

Figure 5 shows that the bellows ie.- evacuated of air pressure and that the steam pressure within the locomotive cylinder I2 has' forced the valve I1 downwardly olf its seat, permitting of the evacuation of the condensation through the lateral port I3.

As shown in Figure 1 the air pipes from the main air reservoir to the drifting valves are shown at 29 and 26, such pipe 29 passing through the cab and having a control valve or cock 3i through which the engineer controls the opening and closing of the cylinder cocks. Y

When the air control valve 3l is open air from the main air reservoir ofthe locomotive flows through the pipes 29 and 26 and into the bellows 22 of the various cylinder cocks raising the valves Il' to a closed position, as shown in Figure 3a.

The drifting valve is shown more particularly in Figures 3, 4 and 6 and consists of a casing 32 having a valve seat 33 therein against which the valve member 34 is adapted to close downwardly under the influence of steam from theboiler which has free access to the chamber above the valve member 34 through the lateral connection 35, shown in Figure 6, and the pipe 36 which connects directly with` the steam dome I4 of the locomotive.

' A valve 31 is shown in theypipe 36. This valve vis at all times open to allow steam from the dome I4 free access to the valve chamber. As shown in Figure 1 an emergency rod'and handle 3B extend from the valve 31 into the cab. Should any damage occur to the drifing valve, the engineer may close the emergency valvel 31, thus preventing leakage of boiler steam from the' dome through the broken drifting valve; or this emergency valve 31 may be closed whenever the drifting valve is in any way incapacitated from operation.

Steam pressure will seat the drifting valve 34 but it is also preferred to employ a coil spring 33 for bearing upon the valve body 34 tending to biasit to a closed position upon the valve seat 33. A

The valve stem extends down through the stuffing box 4I and fits in a socket of top plate 42 which rests on bellows 43. The lower end of bellows 43 has a permanently attached ring flange 44 which extends beneath the bellows housing or casing 45, and a bottom cover plate 66 clamps this ring flange 44 against the casing by means of bolts orother fastenings 41. This particular type of construction forms an air tight expansion chamber and eliminates any possibility of air leaks and the need for lubrication required with pistons and rings. Compressed air is let into the bellows through pipe 48.

Below the drifting valve member 34 a steam delivery pipe 43 connects with the valve casing. As shown inV Figure 2V this pipe 49 is joined at the forward portion of the locomotive with a cross pipe leading to and communicating with both of the locomotive steam chests II. In the pipe 5I) are check valves 5I for preventing the steam chest pressure from getting back into the pipe 49.

The control valve shown more particularly in Figures 3, 4 and 5 includes'an air valve casing 52 having an air closed inlet valve 53 in communication with the air pressure pipe 29 and adapted to close downwardly against a seat 54.

The air chamber 55 beneath the inlet valve communicates freely with the pipe 48 leading to the sylphon bellows. Communicating with the passage 55 is an exhaust port 56 normally closed by a valve 51 which seats downwardly as shown in Figure 4 and is normally seated by the pressure of air in the chamber 55 when locomotive is drifting.

The stems 58 and 59 of the valves 53 and 5l project below the air valve casing and into the path of conical or cam sections 6B and 6I on a piston rod 62. This piston rod 52 carries differential pistons at its end portions, the smaller piston 63 in 'a cylinder 64 of equal size, and a large piston 65 in the large cylinder 66 being both disposed to reciprocate in their respective cylinders. The larger clyinder 65 at its outer end communicates by pipe 51 with the locomotive steam pipe I3 so that superheated steam pressure has access to the outer side of the larger piston 65 at all times while the throttle is open. A bypass pipe 68 connects the outer portions of the small and larger cylinders 64 and 66 and chamber 18, such pipe containing a spring-pressed check valve 69 opening toward the smaller cylinder and chamber to prevent back flow from the smaller cylinder and chamber to the larger cylinder. The port '10 leading to the check valve 53 and by-pass 58 is in the side wall of the cylinder 553 adapted to be masked by the piston 65 when in the position shown in Figure 4 and only uncovered when the piston 55 is in the extreme inner or right hand position illustrated in Figure 3.

A pipe 1I leading from the cross pipe 50 also connects through a port 12 with an intermediate Y portion of the larger cylinder |35 in position to be uncovered by the piston 65 when it moves over to the position shown in Figure 4.

The inner end of the larger cylinder 6B is in communication with a port 13 having a spring loaded check valve 14. The load upon this valve it can be adjusted whereby the valve will open on the presence of predetermined pressure in the inner portion of Vthe larger cylinder 66 when in drifting position, as shown in Figure 4.

The piston rod 62 has a loose lit through the inner head of the larger cylinder 66 as indicated at 'i5 and such head is provided with a valve seat i6 for receiving a valve 'l1 formed on piston rod 62. Communicating with the outer side of the smaller cylinder 64 isa pressure chamber 'i6 in the lower portion of which is a con# densation check valve 1S and in the intermediate portion thereof is an abutment 86 for the piston rod 62. The small cylinder 64 has a port to atmosphere indicated at 8l which is in an intermediate portion of the cylinder to be uncovered by the piston 63 when it moves over tothe eX- treme left position, as shown in Figure d.'

At 82 in Figure 1 is shown the oil. line from the lubricator. Y

In the operation of the device the drifting valve is operated by air pressure from the main air reservoir through the pipes 29 and 48 through the medium of the. control valve and the opening and closing of the cylinder cocks.

The operation with the throttle open cylinder cocks closed-is as follows:-l

When the cylinder cocks are closed, such clos-v and the ing is accomplished by opening the air valve 3l in the cab and admitting air to the pipes 26 and 26. The air pressure in the pipe 29 keeps the air inlet valve 53 closed and the high point of the cam 69 on the piston rod 62 holds the air exhaust valve 5l open, as shown in Figure 3. In this position the drifting valve 34 is closed inasmuch as no air pressure is allowed access to the bellows e3. The control valve is held in the position, shown in Figure 3, by superheated steam pressure passing lfrom the locomotive steamV pipe I3 through pipe 6l to the outer face of the larger piston 65. In this positionl the larger piston 65 has uncovered the port 'Ill but masks the port 'l2 which is oifset to the right from the portv lll. Therefore the superheated steam may pass up through the port 10, openingthe check valve 69 and may pass through the by-pass 69 into the pressure chamber I8, thus having access tothe outer face of the smaller piston 63.

On account of the differential diameters of the pistons this latter pressure will have no effect until the throttle is closed and the superheated steam pressure in the locomotive steam pipe I3 falls. The superheated steam pressure fills the pressure chamberV I8 and actsto close the condensation check 19 which is normally raised by its spring upwardly from its seat, as shown in Figure 4. The position shownin Figure 3 will obtain as long as the throttle is open and the drifting valve will remain closed throughout normal running of the locomotive under steam.

The operation of the parts when the throttle valve is closed is as follows:-

This position of the parts is shown in Figure 4. When the throttle is closed steam in the outer portion of the larger cylinder 66 exhausts through the pipe 6l. VThe steam trapped in the chamber i8 by the non-return check valve 69 moves both pistons 63 and 65 and the piston rod 62 to the left until the valve face 'Il on the piston rod encounters, and closes against, the valve seat '16. Such movement of the parts causes the stem 58 of the air inlet valve 53 to ride up on the cam section 6I of the piston rod 62 to the high point of the cam, thus opening the air inlet valve 53 and air exhaust valve 5'! drops to the low portion of cam closing the exhaust port 56. Air now passes from the pipe 29 through the casing 52 to the pipe 48 and to the drifting valve bellows i3 eX- panding the bellows and lifting the drifting valve 3l! off its seat againstthe action of the boiler pressure above the valve. v

Boiler steam is now free. to` pass directly from the dome hl to the steam chest and cylinders of the locomotive through the pipe i9 and the cross pipe 56. In this position port l'2in the larger cylinder 66 is uncovered by thelarger piston 65 and steam fromthe pipe 'Il passes into and nils the space between the inner face of the pisto-n der 66, the amount of pressure being controlled K by the load on the check valve lli. VNo steam can escape past the shoulder or valve 'll on the piston rod 62 since the pressure on the inner faceof the piston 65 holds this valve face 'il firmlyto Vthe steam tight iit against seat I6. The

port 'I6 is sealed by the piston 65, while the port 6| in the smallerfcylinder 64'is uncovered, allowing steam in the pressure chamber 'i8 to escape and the condensation check Valve 'I9 to open.

The operation when the locomotive slows down is as follows: Y Y

As the locomotive slows down preparatory to stopping, the amount of steam supplied to the locomotive steam chests and cylinders by the drifting valve is greater than can be worked off by the slowly moving locomotive valves and pistons.

Consequently pressure builds up in the steam pipe i3, pipe 61 and outer portion of the larger cylinder 66. When pressure on the outer face of the piston 65 exceeds the pressure on the inner face as controlled by the pressure check valve 14, the piston 65 will move to the right, or to the position shown in Figure 3, unseat-ing the piston rod valve face 11 and releasing steam to the right of piston 65 through the exhaust ports 75. This movement permits closing of the air inlet valve 53 and it opens the air exhaust valve 6l. Air pressure in the bellows i3 is evacu- Vated down pipe i8 and out through passage 55 to the atmosphere. The boiler pressure in chamber 36 forces drifting valve 34 to close. The last stroke or two of thc locomotive main pistons ex hausts whatever steam remains in the steam pipe i3, and, when the locomotive comes to a complete stop, the locomotive steam chests and cylinders are entirely free of steam.

When the engine is placed in the terminal and the cylinder cocks are opened by closing the air valve 3l in the cab, the air pressure is automatically shut off from the control valve and the drifting valve becomes inoperative, so that there is no likelihood of the drifting valve supplying steam to the locomotive which might cause the locomotive to walk off, This forms a safety feature.

It is obvious thatvarious changes and modications may be made in the details of construc tion and design of the above specifically described embodiment of this invention without departing from the spirit thereof, such rchanges Vand vmodifications being restricted only by the the locomotive steam Ychests and. cylinders,r an air pressure device for `opening said drifting valve in controlled communication with the air source,a normally closed airA inlet valve between said source and device,- an air exhaust valve seated by the air pressure' in saidl device, said air inlet valve' and air exhaust valve having stems disposed in proximity to one another, and a control device includingspaced pistons, a connecting rod connecting the pistons together and having cam portions for engaging said rods, said cam portions having their .low points together and their high points apart. whereby to open and close the air inlet and air exhaust valves in reverse relation.

2. In a locomotive having a source of com-V pressed air supply, a normally closed drifting valve for controlling the flow of boiler steam to the locomotive steam chests andY cylinders, an air pressure device for opening said drifting valve in controlled communication with the air source, a normally closed air Vinlet valve betweensaid source and device, an air exhaust valve for evacuating the pressure from said device, and control means comprising dinerential cylinders, pistons of differential diameters therein, means for placing the outer portion of the larger cylinder in communication with the steam chest pressure, a by-pass connecting the outer portions of both cylinders, and a piston rod connecting said pistonsV and disposed lat right angles to said air inlet and exhaust valves and having cam portions for engaging the stems of said air inlet and air exhaust valves.

3. In a locomotive having a source of compressed air supply, anormally closed drifting valve for controlling the flow of boiler steam to the locomotive steam chests and cylinders, an pressure device for opening said drifting valve in controlled communication with the air source, a normally closed air inlet valve between said source and device, an air exhaust kvalve for evacuating said device, and control means comprising large and small cylinders disposed on an axis at right angles to the axes of the air inlet and exhaust-valves, large and small pistons in said cylinders, a piston rod connecting said pistons and having cam portions thereon for engaging the valve stems of said air inlet and-air exhaust valves, means placing the outer portion of the larger cylinder in communication with the steam chest pressure, a by-pass connecting the outer portions of both cylinders, a non-return check in said by-pass for preventing back now from the smaller to the larger cylinder, said smaller cylinder having an evacuation port unmasked by the smaller piston in the drifting position. Y

4. In a locomotive having a source of coinpressed air supply, a normally closed driftingY valve for controlling the flow oif boilersteam to the locomotive steam chests andcylinders, an air pressure device for opening said drifting valve in controlled communication with the air source, a normally closed air inletvalve between said source and device, an air Yexhaust valve for evacuating said device, and control means comprising small and 'large cylinders, small and large istons therein, a piston-rod connectingl said pistons and disposedacross the ends ofrthe'stems of their air inlet and exhaust valves and having cam portions for engaging the stems of said air inlet and air exhaust valves, means'for placing the outerportioniof the larger cylinder in comthe locomotive steam chests and cylinders, an

air pressure device for opening said drifting valve in controlled communication with the air source,

a normally closed air inlet valve between said source and device, an air exhaust valve for evacuating said device, and control means comprising small and large cylinders, small and large pistons therein, a piston'rod connecting said pistons and having cam portions between the ends thereof vfor engaging the stems ofsaid lair inlet and air exhaust valves, meansfor placing the cuter portion of the larger cylinder in communication with the steam chest pressure, a by-pass connecting the outer portions of both cylinders, a non-return check in said by-pass for preventing back iiow from the smaller to the larger cyl-- inder, said smaller cylinder having an evacuation port normally masked by the smaller piston but opened in the drifting position of said smaller piston, said larger cylinder having a port normally masked by the larger piston but uncovered in the drifting position of the larger piston, means for communicating the outer end of the larger cylinder With the steam chest pressure to control movements of the larger piston by pressure inthe steam chest, and a variable loaded valve for controlling evacuation of pressure from the inner portion ofthe larger cylinder.

6. In a locomotive having a source of compressed air supply, cylinder cocks, pipe connections from the air source to said cylinder cocks, anormally closed drifting valve for controlling the flow of boiler steam to the locomotive steam chests and cylinders, an air pressure device for opening said drifting valve in controlled 'coinmunication with the air source, a normally closed air inlet valve-between said source and device, an air exhaust valve for evacuating said device, control means comprising small and large cylinderasmall and'large pistons therein, a piston rod connecting said pistons and having-cam portions between the ends thereof for engaging the stems of said air inlet andair exhaust valves, means for placing the outer portion of the larger cylinder in communication with the steam chest pressure, a by-pass connecting the outer portions of both cylinders, a non-return check in said bypass for preventing backflov/ from the smaller to the larger cylinder, said smaller cylinder having an evacuation port normally masked by the smaller piston but opened in the drifting position of ,said smaller piston, said larger cylinder having a port .in its side wall in communication 'with the steam chest pressure and normally masked by said larger piston but uncovered in the drifting position of the larger piston when the cylinder cocks are open, a variable loaded valve for controlling the exhaust of pressure from the inner portion of the larger cylinder, said larger cylinder alsojhaving a port for free evacuation ,of the-inner portion thereof, said piston rod havnok ing means for closing said last mentioned port in the drifting position of the parts.

7. In a locomotive having a source of compressed air supply, a normally closed drifting valve for controlling the flow of boiler steam to the locomotive steam chests and cylinders, an air pressure device for opening said driiting valve in controlled communication with the air source, a normally closed air inlet valve between said source and device, an air exhaust valve for evacuating said device, control means comprising small and large cylinders, small and large pistons therein, a piston rod connecting said pistons and having cam portions between the ends thereof for engaging the stems of said air inlet and air exhaust valves, means for placing the outer portion oi the larger cylinder in communication with the steam chest pressure, a by-pass connecting the outer portions oi both cylinders, a non-return check in said by-pass for preventing back flow from the smaller to the larger cylinder, said smaller cylinder having an evacuation port normally masked by the smaller piston but opened in the drifting position of said smaller piston, said larger cylinder having a port in its side Wall in communication with the steam chest pressure and leading to the outer side of the smaller piston, said port being normally masked by the larger piston but uncovered in the drifting position of the larger piston, an inner head for said larger cylinder having an evacuation port extending about the piston rod and having a valve seat about said evacuation port, said piston rod having a valve face adapted to take against said valve seat in the drifting position of the parts, a second evacuation port for the inner portion of the larger cylinder, and a spring loaded check valve for controlling exhaust through the last mentioned evacuation port.

8. In a locomotive having a source of compressed air supply, cylinder cocks, pipe connections froin the air source to said cylinder cocks, a cab valve for governing the supply of air to the cylinder cocks, means associated with the cylinder cocks for closing said cylinder cocks when the air pressure is turned on, a drifting valve for regulating the supply of boiler steam to the locomotive steam chests normally closed by the boiler steam pressure, an air pressure device for opening said drifting valve, by-paes connections for placing said device in the air line toisaid cylinder cocks, a normally closed air inlet valve for controlling the supply of air to said device, and control means in communication with the steam chest pressure for regulating the opening and closing or said air inlet valve whereby to open the air inlet valve in the drifting position of the locomotive and to permit it to close at all other times, said control means including spaced cylinders, pistons slidable in said cylinders, and a unitary connecting rod connecting the pistons together and having intermediate cam portions engageable by said inlet valve for opening or closing thereby.

9. In a locomotive, air closed cylinder cocks, an air line to said cylinder cocks, a cab valve for the air line, a normally closed drifting valve openable to permit flow of boiler steam to the locomotive steam chests, an air pressure device for opening said drifting valve, pipe connections from said device to the cylinder cockI air line, a normally closed air inlet valve for regulating the supply of air to said device, an exhaust air Valve for controlling the evacuation of air from said device, and control means movable by the presence and absence of superheated steam pres- Sure in the steam chests for opening and closing said air inlet and air exhaust valves, said control means including spaced cylinders, pistons slidable in said cylinders, and a unitary connecting rod connecting the pistons together and having intermediate cam portions engageable by said inlet valve for opening or closing thereby.

l0. In a locomotive having a source of compressed air supply, a normally closed drifting valve for controlling the flow oi boiier steam to the locomotive steam chests and cylinders, normally open cylinder cocks for the locomotive cylinders, an air pressure device for opening said drifting valve in controlled communication with the air source, a controlled branch connection between the air source and the cylinder cocks for closing the latter when the drifting valve is open, a normally closed air inlet valve between said source and device, and control means for opening said air inlet valve only when the locomotive is drifting with the throttle closed, said control means including spaced cylinders, pistons slidable in said cylinders, and a unitary connecting rod connecting the pistons together and having intermediate cam portions engageable by said inlet valve for opening or closing thereby.

11. In a locomotive having a source of compressed air supply, a normally Yclosed drifting valve for controlling the ilow of boiler' steam to the locomotive steam chests and cylinders, an air pressure device for opening said drifting valve in controlled communication with the air source, normally open cylinder cocks for the locomotive cylinders in controlled communication with the air source, a normally closed air inlet valve between said source and device, a normally closed air exhaust valve for evacuating pressure from said device, control means for alternately opening and permitting the closing of said air inlet valve and said air exhaust valve, and steam chest pressure means operable on said control means to regulate the operation of the drifting valve, said control means including spaced cylinders, pistons slidable in said cylinders, and a unitary connecting rod connecting the pistons together and having intermediate cam portions engageable by said inlet valve for opening or closing thereby.

12. In a locomotive having a source of compressed air supply, a normally closed drifting valve for controlling the now of boiler steam to the locomotive steam chests and cylinders, an air pressure device for opening said drifting valve in controlled communication with the air source, a normally closed air inlet valve between said source and device, an air exhaust valve biased to a closed position for evacuating the air from said device, cylinder cocks in said controlled communication with the air source, and control means having a movable part with cam portions for engaging the stems of said air inlet valve and air exhaust valve to open and close the valves in reverse relation and having valve parts communicating with the steam chest pressure for controlling the control means, said control means including spaced cylinders, pistons slidable in said cylinders, and a unitary connecting rod connecting the pistons together and having intermediate cam portions engageable by said inlet valve for opening or closing thereby.

CHARLES STERN. 

